1. Field of the Invention
The present invention relates to a diagnosing method of quality of a golf swing.
2. Description of the Related Art
When a golf player hits a golf ball, the golf player addresses so that a line connecting right and left tiptoes is approximately parallel to a hitting direction. In a right-handed golf player's address, a left foot is located on a front side in the hitting direction, and a right foot is located on a back side in the hitting direction. In the address, a head of a golf club is located near the golf ball. The golf player starts a takeback from this state, and raises up the head backward and then upward. A position where the head is fully raised up is a top. A downswing is started from the top. A start point of the downswing is referred to as a quick turn. The head is swung down after the quick turn, and the head collides with the golf ball (impact). After the impact, the golf player swings through the golf club forward and then upward (follow-through), and reaches a finish.
In improvement in skill of a golf player, it is important to acquire a suitable swing form. Swing diagnosis is conducted so as to contribute to the improvement in the skill. In the swing diagnosis, a swing is photographed by a video camera. The swing may be photographed in order to collect materials useful for development of golf equipment.
In classic swing diagnosis, a teaching pro or the like views a moving image and points out problems during a swing. On the other hand, an attempt to diagnose the swing using image processing is also conducted. In the image processing, a frame required for diagnosis needs to be extracted from a large number of frames. It is necessary to extract a silhouette of a photographic subject from these frames. An example of a method for extracting the silhouette of the photographic subject is disclosed in Japanese Patent Application Laid-Open Nos. 2005-210666 (US2005/0143183) and 2011-78069.
In the method disclosed in Japanese Patent Application Laid-Open No. 2005-210666, the photographic subject and a background scene are distinguished by using difference processing. The silhouette of the photographic subject is extracted by the difference processing. In the method disclosed in Japanese Patent Application Laid-Open No. 2011-78069, the photographic subject and the background scene are distinguished by using a silhouette extracting method. In the silhouette extracting method, the silhouette of the photographic subject is extracted by using a luminance histogram and a color histogram of a pixel constituting the frame.
For example, a predetermined silhouette such as a silhouette of an address is specified from the plurality of extracted silhouettes. The quality of the swing is decided from the specified silhouette. Quality judgement can be automated by extracting suitable information from the silhouette. When the extracted information is suitable, the quality of the swing can be accurately decided.
It is an object of the present invention to provide a method capable of readily and accurately diagnosing quality of a swing.